What do Trees Know?

My son, Kaveh, and I have been taking a walk before school. This is not so easy on a weekday, but it is a high priority. We might make it around a block or two in ten minutes, and I am never, ever sorry. Here is why.

On a recent morning walk, in the brisk fall air, we were discussing the notion that engineers can learn from nature’s designs. I was explaining to Kaveh how the biologist Robert Full has been working with engineers to see how nature’s designs can solve engineering problems (See Robert Full on Ted.com). The engineers at Berkeley come to him with questions, and he tries to answer them by learning how nature has solved the problem. This partnership has helped to produce robots that are more stable (like cockroaches) and more capable (like Geckos who can climb vertical glass walls).

While Robert Full studies animals, Kaveh and I took this notion of nature informing engineering to the observation of trees. Kaveh has had the good fortune to grow up on a tree-lined street. There are many species of established oaks, sycamores, poplars, crepe myrtles, elms, and other varieties, and over the years we have seen them respond to change. For example, they survived hurricane Ike by bending to the ground in 110 mile-an-hour winds, and they conserved water in the drought of 2012 by dropping smaller branches and sending tiny leaves out along the remaining limbs.

So we have long been rooting for the trees. ;-)

And this fall, on our morning walk, they were beautiful in their autumn colors. They drew our eyes upward, where we could see flaming leaves heaving up over the street.

Our discussion of engineering and nature veered to what engineers might learn about solar power.

“What do trees know about solar power?” I asked

“I don’t know, that the sun moves?” said Kaveh.

And suddenly, we both had an epiphany. In looking at the rounded shape of the trees, the direction of the branches, the angle of the leaves, it all made sense. The tree was simply reaching for the light. Long experience had taught trees that the light is always changing. It changes throughout the day, and it changes through out the year. One side of the tree collects sunlight in the morning and another side in the afternoon. The distribution of branches and leaves, even the shape of the leaves can all be explained by the simple elegant notion that the tree knows where the sunlight is, and it is gathering that sunlight in the most efficient way possible.

The beautiful gnarled limbs of our beloved live oaks evolved not only to catch sunlight as it crosses the sky each day, but also as it changes it’s position from summer to winter.

“Could solar panels do that?” I asked.

“Maybe,” said Kaveh.

We compared the oak to a tropical palm in a neighbor’s yard. Its broad leaves seemed designed for a sun that crosses the top of the sky, which would make sense closer to the equator. Then we talked about the triangle-shaped pines that we see in the north, and how they are suited to gathering light from a sun that goes around the perimeter of the sky.

We were only halfway around the block when this epiphany struck, but suddenly it was as if we understood the world, nature, sunlight, and solar power in a completely new way.

If we had not taken the time to go for that walk, this conversation might never have happened. Now I am more determined than ever to make these walks happen, for there is much more to learn from our wise old friends.